The invention refers to a roller conveyor track, in particular for a track with small-diameter rollers for work piece carriers, as well as a roller chain for a roller conveyor track.
A skate wheel conveyor, i.e. a roller conveyor track for low-weight loads is known from the German company publication of the Mannesmann Dematic AG, Wetter, bearing the title "Demag--Modular Concept Transfer System (DTS [MCTS]) (see edition of 01/1997, page 17). Essentially, this conveyor track with small-diameter rollers consists of two parallel, spatially separated support elements that extend in the conveying direction, and from which the goods units--preferably work piece carriers for the assembly operation--can be conveyed and supported at their respective lateral lower surfaces. For that purpose, the extruded aluminum sections are provided--seen in cross section--with an upper and lower hollow space, both extending in the conveying direction. The upper hollow space is provided with a slot-like, longitudinal aperture in the conveying direction, inside and along which extend the support rollers of the skate wheel conveyor track, that are placed in the hollow space in direction of the goods units. In order to simplify the assembly, the support rollers are not individually installed in the support elements, but are components of a so called roller accumulator chain, which--seen in the conveying direction--shows multiple support rollers that are consecutively but separately arranged, such as are normally utilized in roller accumulation chain conveyors. In order to mount the support rollers, the roller chain is inserted into the upper hollow space and, in order to prevent it from slipping inside the support element, it is fixed--pointing upstream viewed in the conveying direction--at the beginning of the support element via a bolt. Thereby, the support rollers of the chain and, thus, the support rollers of the conveyor track rest on the bolts of the roller accumulator chain as well as between its side bars. Since a roller accumulator chain is used for the conveyor track that is described here, same clearly shows extended bolts that jut out laterally from the chain's side bar upon which the respective track rollers rest. The track rollers are supported by the lower part of the upper hollow space in this manner to achieve free tunability of the track rollers. In one special design, one of the two support elements can be provided with a small-diameter roller track with inserted roller accumulator chain, and the other support element can be provided with a driven, continuous flat belt, which allows the transported goods to be moved on the conveyor track.
Especially in the case of conveyors of this design it may happen that--due to the headroom of the roller accumulator chain--the flat belt will have to be lifted by additional means in order to be able to convey the transported goods horizontally. For this purpose, for instance plastic, ledge-shaped sections are attached to the upper surface of the support elements on which the conveyor belt then proceeds.
The previously described roller accumulator chains that are utilized for this type of roller conveyors are described as components of conveyors with roller accumulator chain, such as referred to, for instance, in the German disclosure publication DE 34 32 042 A1, showing support rollers that serve to accept the transported goods, and which rest both on the chain's bolts as well as between the side bars. The chain pitch is selected to let the rollers turn freely. In the case of conveyors with roller accumulator chains, the continuous chains are arranged and supported by the support elements via track rollers. The track rollers rest on the respective bolts of the chain, which--for this purpose--have been lengthened in order to jut out from the side bars on both sides.
In connection with the previously described roller conveyor tracks that use continuously cast aluminum sections with upper and lower hollow spaces, these sections can also be utilized as support elements for conveyors with roller accumulator chains (see page 16 of the previously mentioned German company publication of the Mannesmann Dematic AG), and serve to return the lower strand of the roller accumulator chain to the lower hollow part of the support element.